plating, anodizing, & finishing Q&As since 1989
Best lining for concrete retaining pit for Anodize Line
June 5, 2012
Q. I am looking for recommendations on a lining or sealer for the concrete in our retainment pit for our anodizing line. We have used urethane in the past and over time it does not stand up well to to chemicals. I had someone suggest Rhino Liner, but I am looking for anyone who has had a good experience with a coating or sealer that has done well over time.
- Murfreesboro, Tennessee, USA
A. Hi Bryant. A trowel-on glass reinforced vinylester can be very robust, very corrosion resistant, and should introduce no new problems. Spray-on coatings are similar, but thinner, so not as robust. As for urethane liners, I understand their use and attraction, but don't really like them if they are ever walked on because they can introduce slip-and-falls.
If this "retainment pit" is secondary containment, i.e., is designed to be dry but capture an occasional spill (like the floor underneath the anodizing line), I think the vinylester trowel-on would be perfect.
But if this pit is a primary containment device (holding tank dumps, for example) you are not going to like the following answer because it makes a suggestion that is awfully expensive :-(
To understand the suggestion, you need to start from the premise that every liner will eventually crack or otherwise fail -- a premise that has been borne out in hundreds of old revamped or de-commissioned plating shops. I was involved in the complete revamp of only one very old plating shop that required no soil remediation, and that was because a liner existed in the gravel below the concrete. So that is my expensive suggestion. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I agree with Ted. The most robust liners are multilayer with a PVDF surfacing veil under the top layer. Basically, it is building a fiberglass tank inside your pit.Lyle Kirman
consultant - Cleveland Heights, Ohio